The goal of this study is to determine whether the localization of activation signal in the primary motor cortex by fMRI and retrospective motion correction is precise enough to allow its use in preoperative decision making. The functional localization with fMRI will be validated with the direct intraoperative and extraoperative stimulation mapping as truth. The spatial sensitivity and specificity of fMRI localization will be evaluated by robust comparison with the truth using a series of patient data. A volumetric mapping implementing mutual information will be utilized for the precise cross referencing of the functional localization of fMRI with the direct cortical mapping in the patient?s anatomical reference coordinates. The loss of sensitivity and specificity in functional localization due to subject motion is widely observed in fMRI. Despite the widely recognized potential, the use of fMRI has been limited to cooperative patients and tasks requiring no motion. With the motion related artifacts, to date, the sensitivity and specificity of fMRI's localization have not been optimized. The study utilizes a retrospective motion correction method to map slice to volume (MSV), which is applied to multi slice single shot echo-planar image (EPI) data. Individual slices are spatially repositioned into an anatomical reference volume space to accommodate out-of-plane and in-plane subject motion. The MSV approach implements automatic optimization of mutual information as a matching criterion. The MSV approach has unique motion correction capabilities for multi slice fMRI time series data. The preoperative, non-invasive localization capabilities of fMRI with motion correction can facilitate planning of operations near functionally important brain areas as well as decision to choose an operative or non-operative treatment. The correction of patient motion artifacts is significant for the accurate geometric localization of the functional assessment for presurgical planning. The MSV approach will enable functional localization of the task paradigms requiring the task associated motion, i.e. overt speech. This study proposes that fMRI mapping can be successfully obtained routinely in patients with cerebral tumors despite the inconsistencies in patient cooperation and task-related motion artifacts.